The present invention relates to an ice composition excellent in freezing ability and bactericidal activity. The invention further relates to a method of storing a perishable food, e.g., a fresh fish, vegetable, or fruit, with the ice composition.
Cooling with ice is generally known as an effective technique for food storage. In cooling with ice, the temperature of the food is lowered to about 0 to 5xc2x0 C. and the putrefying and other bacteria adherent to or contained in the food are inhibited from propagating. However, this technique is frequently insufficient for fully inhibiting putrefaction and attaining freshness preservation and is hence unsuitable for long-term storage.
Under these circumstances, an ozonized ice obtained by dissolving ozone in water and freezing the ozonized water has been proposed as a material for perishable food storage which is more effective than the storage based only on the cooling power of ice (see Japanese Patent Laid-Open Nos. 131865/1989 and 294911/1999). Ozonized water is generally produced by a method in which ozone generated by electric discharge in air or oxygen or by water electrolysis with a solid electrolyte is dissolved in water.
However, in such ozonized water, most of the ozone is dispersed as fine bubbles in the water and dissipates into the air in a short period of time. Because the ozone concentration thus decreases, there is a problem that a sufficient effect of freshness preservation and a sufficient bactericidal effect do not last. Furthermore, use of an ozonized ice has the following drawbacks. Since an ozonized ice generates ozone while melting, the bactericidal effect of ozone long continues when the initial ozone concentration is high. Virtually, however, there is a problem that even when high-concentration ozonized water is frozen, the ozone concentration decreases considerably during the freezing step. It is therefore necessary to conduct preliminary cooling, quick freezing, or the like for actually producing a high-concentration ozonized ice capable of retaining bactericidal activity and freshness-preserving properties over a long period of time. At present, investigations are being made on processes for producing the ice. Although various apparatus have been proposed based on the investigations, they have complicated structures and this is an obstacle to practical use thereof. Furthermore, since ozone is sparingly soluble in water, it is difficult to produce high-concentration ozonized water and this constitutes an obstacle to the production of the ozonized ice.
Besides ozone, which has such drawbacks, hydrogen peroxide is known as a compound having bactericidal activity. It has been proposed to eject particles of an ice containing hydrogen peroxide onto a semiconductor to clean it (see Japanese Patent Laid-Open No. 49224/1991).
In this method of cleaning, not only the ice particles ejected physically remove impurity particles, fouling substances, etc., from the surface of the semiconductor substrate, but also impurities which cannot be physically removed are removed by the chemical action of hydrogen peroxide to further conduct surface modification. In this cleaning method, since hydrogen peroxide is produced by the discharge method, impurities are apt to come into the hydrogen peroxide. This ice hence has a drawback that it is less suitable for application to foods. Namely, the ice containing hydrogen peroxide (ice composition) disclosed in that reference is intended only for use in cleaning, and there is no description therein concerning the storage of foods.
The present invention has been made in view of the drawbacks of the related-art techniques described above.
Accordingly, one object of the present invention is to provide an ice composition suitable for use in the storage of perishable foods.
Another object of the present invention is to provide a method of storing a perishable food with the ice composition.
According to one embodiment of the invention, an ice composition containing hydrogen peroxide is provided, the composition being obtained by freezing an aqueous hydrogen peroxide solution prepared by electrolyzing water.
According to another embodiment of the invention, a method of perishable food storage is provided which comprises adding an ice composition containing hydrogen peroxide to a perishable food and storing the perishable food with the aid of the bactericidal activity of the hydrogen peroxide and the freezing ability of the ice composition.